Air flow measuring device

ABSTRACT

An air flow measuring device includes a sensor assembly, a thermistor, and an end terminal. The sensor assembly includes a sensor portion and a sensor circuit. The sensor portion and the sensor circuit are integrated with each other and configured to measure an air flow quantity. The thermistor is equipped independently from the sensor assembly. The thermistor is configured to measure an air temperature. The end terminal is electrically connected with the sensor assembly and the thermistor. An external connection terminal in the sensor assembly is electrically connected with the sensor portion and the sensor circuit to function as the end terminal.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on reference Japanese Patent Application No.2013-99164 filed on May 9, 2013, the disclosure of which is incorporatedherein by reference.

TECHNICAL FIELD

The present disclosure relates to an air flow measuring deviceconfigured to measure a quantity of air flow.

BACKGROUND

For example, Patent Document 1 discloses a conventional air flowmeasuring device, which includes a sensor assembly and an end terminalmolded in a resin housing (passage formation member). More specifically,in the sensor assembly according to Patent Document 1, a sensor circuit(control circuit) is molded in a primary molding resin. In addition, anexternal connection terminal, which is for electrically connecting thesensor circuit with an external device of the sensor assembly, is alsomolded in the primary molding resin.

Furthermore, the external connection terminal, which is exposed to theoutside of the primary molding resin, is electrically joined with an endterminal, which is manufactured separately from the external connectionterminal. Subsequently, the sensor assembly and the end terminal aremolded with a resin housing. End of the end terminal is exposed in aresin coupler, which is molded with the resin housing.

It is noted that, in the conventional configuration according to PatentDocument 1, the external connection terminal of the sensor assembly isformed separately from the end terminal, and therefore, the conventionalconfiguration may require an additional number of components. Inaddition, the conventional configuration may require an additionalassembling and joining process to join the external connection terminalwith the end terminal mechanically and electrically. Therefore, theconventional configuration may incur additional cost for manufacturingthe air flow measuring device. In addition, the conventionalconfiguration may require margins, via which the external connectionterminal is joined with the end terminal, and therefore, theconventional configuration may incur additional manufacturing cost andadditional volume of the device.

Patent Document

Publication of unexamined Japanese patent application No. 2011-106868

SUMMARY

It is an object of the present disclosure to produce air flow measuringdevice with reduced number of components, simplified manufacturingprocess, reduced cost for component, and/or reduced volume forcomponent. According to an aspect of the present disclosure, an air flowmeasuring device comprises a sensor assembly including a sensor portionand a sensor circuit, which are integrated with each other andconfigured to measure an air flow quantity. The air flow measuringdevice further comprises a thermistor equipped independently from thesensor assembly and configured to measure an air temperature. The airflow measuring device further comprises an end terminal electricallyconnected with the sensor assembly and the thermistor. An externalconnection terminal in the sensor assembly is electrically connectedwith the sensor portion and the sensor circuit and configured tofunction as the end terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription made with reference to the accompanying drawings. In thedrawings:

FIG. 1 is a schematic sectional view showing a main portion of an airflow measuring device; and

FIG. 2 is a schematic sectional view showing the air flow measuringdevice equipped to a duct.

DETAILED DESCRIPTION First Embodiment

A first embodiment of the present disclosure will be described withreference to FIGS. 1 and 2. An air flow measuring device 1 is equippedto an air intake duct 2, which is to draw intake air to an internalcombustion engine of a vehicle when the vehicle is, for example,travelling. More specifically, the air intake duct 2 is equipped to, forexample, a duct, which is located at an outlet of an air cleaner, orequipped to an intake pipe at a downstream of an air cleaner.

The air flow measuring device 1 is a thermal airflow meter configured tomeasure a quantity of intake air (intake air quantity, air flowquantity) drawn into the engine.

The air flow measuring device 1 includes a resin housing 3, a sensorassembly 6, and end terminals 8. The resin housing 3 (passage formationmember) is equipped to the air intake duct 2. The sensor assembly 6includes a sensor portion 4 and a sensor circuit 5, which are integratedwith each other. The sensor portion 4 is configured to measure the airflow quantity. A thermistor 7 is equipped independently (separately)from in the sensor assembly 6. The thermistor 7 is configured to measurea temperature of intake air (air temperature). The end terminals 8 areconfigured to electrically connect the sensor assembly 6 with thethermistor 7.

The resin housing 3 is a secondary-molded product of resin. The interiorof the resin housing 3 forms a bypass passage a and a sub-bypass passage13. The bypass passage a is configured to draw a part of intake air,which flows through the air intake duct 2. Specifically, the air intakeduct 2, which is equipped with the air flow measuring device 1, has anAFM mount hole. The AFM mount hole extends through the air intake duct2. The AFM mount hole may communicate the inside of the air intake duct2 with the outside of the air intake duct 2. A main portion of the resinhousing 3 is inserted from the outside of the AFM mounting hole into theair intake duct 2. Mores specifically, a portion of the resin housing 3,which forms the bypass passages α and β, is inserted into the air intakeduct 2. Subsequently, the resin housing 3 is fixed to the air intakeduct 2 by, for example, fastening the resin housing 3 to the air intakeduct 2 with a tapping screw. In this way, the air intake duct 2 isequipped to the air flow measuring device 1.

The sensor portion 4 is inserted into the sub-bypass passage β. Thesensor portion 4 is configured to generate, for example, a voltagesignal according to the a quantity of intake air flow, which is a partof intake air flow passing through the sub-bypass passage β. In thepresent example, the sensor portion 4 employs a chip-form configuration.More specifically, the sensor portion 4 is configured with, for example,a thin film-type circuit board. The sensor circuit 5 is configured tocompensate the quantity of intake air flow detected with the sensorportion 4. The sensor circuit 5 is further configured to A/D convert thecompensated quantity of intake air flow and to send a signalrepresenting the quantity of intake air flow. The sensor circuit 5 mayimplement, for example, frequency modulation on the compensated quantityof intake air flow.

The sensor assembly 6 is formed by integrally molding the sensor portion4 and the sensor circuit 5 of primary molding resin. More specifically,the sensor portion 4 has a section, which includes a sensor circuitboard and excludes an air flow quantity measurement element, and thesection of the sensor portion 4 is integrally molded with the sensorcircuit 5. Subsequently, the sensor portion 4 and the sensor circuit 5,which are integrally molded together, are further molded with the resinhousing 3. The sensor circuit 5 is molded with the sensor assembly 6 andis further connected electrically with an ECU (engine control unit)through a connector 9. The connector 9 is equipped to the resin housing3 and located at an upper portion of the resin housing 3 in the drawing.The ECU is located in the vehicle at a position different from aposition at which the air flow measuring device 1 is located.

The connector 9 includes a resin coupler 10 and the end terminals 8. Theresin coupler 10 is formed as a part of the resin housing 3. The endterminals 8 are exposed at those ends inside the resin coupler 10. Asshown in FIGS. 1 and 2, the connector 9 is a male connector includingthe resin coupler 10 and the end terminals 8. The resin coupler 10 isformed in a female shape. The end terminals 8 are projected from abottom surface of the resin coupler 10 into the resin coupler 10. In thepresent embodiment, the end terminals 8 includes an electric powersource end terminal 8 a, a grounding end terminal 8 b, a flow output endterminal 8 c, a control end terminal 8 d, a temperature output endterminal 8 e, and/or the like.

The connector 9 described above is one example and may be modifiedarbitrarily. For example, the connector 9 may be a female connector,dissimilarly to the present embodiment. In addition, according to thepresent embodiment, the connector 9 is configured to receive a connecteddevice at its upper portion from its upper side. It is noted that, theconnector 9 may receive a connected device at its side portion in alateral direction. The arrangement of the end terminals 8 is one exampleand may be modified arbitrarily.

The sensor assembly 6 includes external connection terminals 11. Theexternal connection terminals 11 are configured to be connectedelectrically with the sensor portion 4 and/or the sensor circuit 5. Theexternal connection terminals 11 are configured to connect the sensorportion 4 and the sensor circuit 5 electrically with an external device.The external device is outside a molded product, which is molded of theprimary molding resin to form the sensor assembly 6. That is, theexternal connection terminals 11 are common to the end terminals 8. Inother words, the external connection terminals 11 are formed of commoncomponents with the end terminals 8.

Specifically, the external connection terminals 11 according to thepresent embodiment are formed by implementing a press working to punchthe external connection terminals 11 out of a metal plate, which isexcellent in conductivity. The metal plate is, for example, a copperthin plate. The external connection terminals 11 are formed in this way,thereby to simultaneously from the electric power source end terminal 8a, the grounding end terminal 8 b, the flow output end terminal 8 c, thecontrol end terminal 8 d, and the temperature output end terminal 8 e.The grounding end terminal 8 b also serves as a grounding electrode ofthe sensor portion 4, the sensor circuit 5, and the thermistor 7. Thesensor portion 4 and the sensor circuit 5 are equipped to the groundingend terminal 8 b in the sensor assembly 6. The sensor portion 4 and thesensor circuit 5 are connected by way of an electric connection element,such as a bonding wire, with corresponding end terminals, such as theelectric power source end terminal 8 a, the grounding end terminal 8 b,the flow output end terminal 8 c, the control end terminal 8 d, and/orthe like.

To the contrary, the thermistor 7 is located outside the resin housing 3and exposed to the exterior of the resin housing 3. Specifically, thethermistor 7 is a resistive element, which changes its resistanceaccording to change in temperature. One lead wire of the thermistor 7 isjoined electrically and mechanically with an end of the grounding endterminal 8 b. The end of the grounding end terminal 8 b is exposed tothe interior of the air intake duct 2. The other lead wire of thethermistor 7 is joined electrically and mechanically with an end of thetemperature output end terminal 8 e. The end of the temperature outputend terminal 8 e is exposed to the interior of the air intake duct 2.

It is noted that, the portions of the end terminals 8, which are joinedwith the thermistor 7, may be restricted from being exposed directly toair, dissimilarly to the present embodiment. That is, the end of thegrounding end terminal 8 b and the end of the temperature output endterminal 8 e, which are joined with the thermistor 7, may be restrictedfrom being exposed directly to air. That is, the thermistor 7 may befirst joined with the grounding end terminal 8 b and the temperatureoutput end terminal 8 e of the end terminals 8, and subsequently, thejoined portions between the thermistor 7 and the end terminals 8 may bemolded with the resin housing 3.

Effect

As described above, in the air flow measuring device 1 according to thepresent the embodiment, the external connection terminals 11 of thesensor assembly 6 also functions as the end terminals 8 of the sensorassembly 6 and the thermistor 7. Thus, the present configuration enablesto reduce the number of components in this way, compared with aconventional configuration. In addition, the present configurationenables to omit an assembling and joining process, which is formechanically and electrically assembling and joining the externalconnection terminals 11 with the end terminals 8, from entiremanufacturing process for the air flow measuring device 1. Thus, thepresent configuration enables to reduce a manufacturing cost for the airflow measuring device 1.

In addition, the present configuration enables to integrate(commonalize) the external connection terminals 11 with the endterminals 8. Therefore, the present configuration enables to reduce acost incurred for joining the external connection terminals 11 with theend terminals 8. Thus, the present reduction in manufacturing costenables to reduce entire cost for the air flow measuring device 1. Inaddition, the present configuration enables to reduce margins via whichthe external connection terminals 11 are joined with the end terminals8. Therefore, the present configuration enables to downsize the air flowmeasuring device 1.

Industrial Applicability

According to the above embodiment, the configuration of the presentdisclosure is applied to the air flow measuring device 1 configured tomeasure a quantity of intake air drawn into the engine. It is notedthat, the configuration of the present disclosure may be applied to anair flow measuring device, which is for a device other than an engine.

As described above, the air flow measuring device according to thepresent disclosure includes the sensor assembly having the externalconnection terminal(s). The external connection terminal(s) alsofunctions as the end terminal(s) of the sensor assembly and/or thethermistor. Therefore, the present configuration enables to reduce thenumber of components. In addition, the present configuration enables toomit the assembling and joining process, which is for joining theexternal connection terminal(s) mechanically and electrically with theend terminal(s). Furthermore, the present configuration enables toreduce the margins via which the external connection terminal(s) isjoined with the end terminal(s). Therefore, the present configurationenables to reduce the manufacturing cost and the size of the air flowmeasuring device.

It should be appreciated that while the processes of the embodiments ofthe present disclosure have been described herein as including aspecific sequence of steps, further alternative embodiments includingvarious other sequences of these steps and/or additional steps notdisclosed herein are intended to be within the steps of the presentdisclosure.

While the present disclosure has been described with reference topreferred embodiments thereof, it is to be understood that thedisclosure is not limited to the preferred embodiments andconstructions. The present disclosure is intended to cover variousmodification and equivalent arrangements. In addition, while the variouscombinations and configurations, which are preferred, other combinationsand configurations, including more, less or only a single element, arealso within the spirit and scope of the present disclosure.

What is claimed is:
 1. An air flow measuring device comprising: a sensorassembly including a sensor portion and a sensor circuit, which areintegrated with each other and configured to measure an air flowquantity; a thermistor equipped independently from the sensor assemblyand configured to measure an air temperature; and an end terminalelectrically connected with the sensor assembly and the thermistor,wherein an external connection terminal in the sensor assembly iselectrically connected with the sensor portion and the sensor circuitand configured to function as the end terminal.
 2. The air flowmeasuring device according to claim 1, wherein the air flow measuringdevice is configured to measure a quantity and a temperature of intakeair drawn into an engine for a vehicle, the air flow measuring devicefurther comprising: a resin housing defining a passage therein to flow apart of intake air, wherein the sensor portion is equipped to aninterior of the passage, and the thermistor is equipped to an exteriorof the resin housing.